condition mean min max ZT0-3 1.6621528115 1.473862459 1.850443164 ZT4-7 2.6329240175 2.314195988 2.9516520470000005 ZT8-11 2.92955650875 2.652899793 3.2062132245 ZT12-15 3.71248519325 3.644227746 3.7807426404999998 ZT16-19 4.890445002250001 4.1919718790000005 5.5889181255 ZT20-23 7.613959101000001 7.20579614 8.022122062000001